Cowl Flaps on M20K (231)

[tomatl]

Could someone please help me out understanding the cowl flaps on the 231. I understand that they should be continuously adjustable. However, on my airplane they only work full in or full out position. Anything in between causes them to deploy fully, the control moving out. This makes cooling adjustments at higher altitudes difficult. Any idea how to fix this (my mechanic does not know either)?

 

 

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[kortopates]

No, they're not fully adjustable. As described in your POH, they they have 3 position. Closed, in trail and fully open. If they won't stay in-trail position, see Cowl flap rigging in the service manual. The 252's have continuously adjustable cowl flaps and if you do have one of the conversions, such as 262, (a 231 converted to the 252 engine -MB), then you may have some form of the continuously adjustable cowl flaps - but not in a 231.

No Mooney specific transition training? Suggest you attend the next MAPA PPP when its near you. There are several a year all across the country.

Edited July 5, 2019 by kortopates

[tomatl]

Thanks. My problem is that the trailing position does not work and I would appreciate to learn how it can be adjusted, so I can tell my mechanic. Don‘t see what that has to do with a transition training or the Safety Foundation course, which I also recommend to everyone.


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[carusoam]

The value of Transition Training.... are the Mooney Specific CFIIs...

Your CFI can review all of the controls available to you as a pilot...

This flap control issue is just one of the things they would have been able to point out...

Similar To flaps not stopping in the right position, or passing all the way  through to the next position...

Of course, they have the experience to fly the plane with IFR precision...

And... there is always that extra aviation knowledge that makes each CFII unique... some are mechanics and really know how to analyze an engine’s data...

I took three important steps to buying a plane...

1) Select the right Mooney...

2) Select the right person to supply a PPI...  plane was fully tested in IFR flight as well...

3) Transition Training... was to make sure the pilot was up to speed with all the intricacies of the aircraft...

4) MAPA... I had the good fortune to see this training up close, and meet other Mooniacs doing their recurrent training. Many were taking the opportunity to be come current on some odd approaches including a PAR (radar) approach... fun to be part of those discussions with other ordinary Mooney pilots.

Biggest surprises of TT for my O...  no cowl flaps to not work...  and how fast a Mooney can really fly...

For Somebody more experienced... you probably look forward to going through lots of motions looking for the one nugget that surprises you...

For this, you pay a lot... eat up some time... to be happy about learning some thing new...

you feel relieved when that new thing isn’t Take-off distances or stall characteristics of the plane...

Nobody knows engine cooling issues like a good Savvy CFII... how many of those are there that know Mooneys too?

PP thoughts only, not a mechanic...

Best regards,

-a-

[gsxrpilot]

Transition training from a Mooney specific CFI would have been able to explain the proper operations of a 231, including high altitude operations. 

It also sounds like someone's taking their 911 Carrera to a Chevy mechanic. 

[tomatl]

I agree with all these points. I really loved the CFIs at the MAPA training, and I will attend another one (my goal is one a year) this September. Everyone with a Mooney should attend these. If anyone knows of a good  "Mooney CFI" in Western NY, I would also appreciate a hint. Always happy to refresh training.

My issue, however, is not that I don't know how use my cowl flaps (at least I think I do:) but that they started to behave differently after I got the plane back from the shop last months after replacement of two cylinders. They don't stop at the trailing position any more and unless they are fully in, are pulled out in flight to full open, judging by the position of the lever. (Also, after cylinder replacement, cylinder #1 appears to be running much hotter than before, so in combination not an ideal situation.) I did consult the service manual but that does not address this situation either but just explains how to adjust the lengths of the rods. I did learn though, that the trailing position is aerodynamically triggered, and not adjustable continuously as I had thought previously. 

The underlying problem is that in my part of the country we don't have any shop truly familiar with Mooneys. No, I don't take my 911 to a Chevy mechanic but to a Mooney Center - but I never see any Mooney other than mine at this particular shop.

[carusoam]

Tom,

what year is your K?

Are the powered flaps original to your bird or an update that was added later?

I’m not familiar with the powered cowl flaps, sensors or relays... but...

i know a guy...

Best regards,

-a-

[tomatl]

It's is a 1984. I don't have the powered cowl flaps/sensors, etc, just the simple push rod that operates the scissor/spring mechanism manually. Somehow the mechanic must have inadvertently made some adjustments. When I picked it up, the flaps also got pulled out from the fully closed position, then after further adjustments that worked again, but the trailing position has been disabled since.

[carusoam]

See if @M20Doc has any guidance... (‘84 M20K cowl flap motion control question...) MSer has lost trailing flap position...

Best regards,

-a-

[tomatl]

Will do, thanks so much!

[DanM20C]

This might not really be a cowl flap problem.  "In trail" the knob is usually most of the way out. It looks like they are full open but you can move it a bit further and feel the over center latch.  The difference from in trail to full open can been seen on the airspeed indicator, just a few kts slower.  

Do you have a GB or LB?

Intercooler?

Did you have temp problems before the cylinder replacements?

Cheers,

Dan

 

 

[tomatl]

Thanks Dan,

That's precisely how it was before I got the plane back. Now, I cannot move the knob out further, and there is also no "over center" effect. 

I have the LB with Intercooler, Gami Injectors, and Merlyn WG. Never had a temperature issue before replacement. When I got the plane back, even after run in, temp on #1 kept creeping up to 410. Yesterday, I flew to the shop to have the cylinder inspected again. We cleaned the injectors, which had some worn out rubber gaskets (wonder why they did not see this when they put the new cylinder in), and the CHT probe was very loose, which was tightened. On the way back, #1 temp was a bit better, about 380 at 75% power at 3000'. I have to check at altitude ...

[DanM20C]

Sounds like you do need to rig your cowl flaps. 

As for the higher temps, it could just be the cylinders are not fully broke in yet. Or..

Any chance the shop wasn't overly carful with reinstalling the baffling? If #1 was replaced they probably would have removed the oil cooler to do so.  The area around the oil cooler has all sorts of gaps that if not properly addressed will effect chts.  

Cheers,

Dan

[tomatl]

Hi Dan,

Sounds like. Problem is the local Mooney Service Center does not know how to do that.

The cylinders should be fully broken in by now (12+ hours). After my first experience of the high temperatures on #1, they sealed off all the gaps in the baffling with black sealant (was not needed before the cylinder change). This resulted in a drop of temperatures by about 10 degrees. Instead of 410, it kept going up to 400 at 75% and low altitudes with cowls closed. (Could not trail b/c that does not work right now.) Now I am at 380, with the latest fiddling. Perhaps it was the probe that was not properly grounded b/c they "forgot" to screw it in fully?

I thought the oil cooler was on the #2 side (left)? #2 is actually my coolest running cylinder.

Cheers,

Tom

[DanM20C]

Tom, 

Yes the oil cooler is next to #2,  but I believe it needs to be removed to access the through studs for #1. 

Breaches in baffling won't necessarily effect the closest cylinders.  So gaps around the oil cooler could manifest in higher chts in #1.

Get the cowl flaps squared away first. I found that having mine about 1/4" to 3/8” open when in the closed possition keeps my engine happy.

Cheers,

Dan

[tomatl]

Thanks Dan! Making the adjustment you suggest for the summer is probably a good idea.

[81X]

On 7/5/2019 at 1:31 AM, tomatl said:

Hi Dan,

Sounds like. Problem is the local Mooney Service Center does not know how to do that.

The cylinders should be fully broken in by now (12+ hours). After my first experience of the high temperatures on #1, they sealed off all the gaps in the baffling with black sealant (was not needed before the cylinder change). This resulted in a drop of temperatures by about 10 degrees. Instead of 410, it kept going up to 400 at 75% and low altitudes with cowls closed. (Could not trail b/c that does not work right now.) Now I am at 380, with the latest fiddling. Perhaps it was the probe that was not properly grounded b/c they "forgot" to screw it in fully?

I thought the oil cooler was on the #2 side (left)? #2 is actually my coolest running cylinder.

Cheers,

Tom

How lean are you running/ TIT?  This makes a huge difference in keeping my CHTs below 380 in all phases.  

[tomatl]

I run the TIT at around 1500 deg. My CHT, with closed cowl flaps, were never above 375 deg, for all flight situations that I experienced. The problem arose with the new cylinders and the fiddling of my mechanic with the cowl flaps. Next time I fly, I‘ll open them up a bit in closed position, such as suggested by Dan and see what happens. How do you run your engine in cruise?


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[81X]

1500 at 28” or so should keep CHTs right near 380 on the hottest for many normal environments.

I run about 1480 TIT at 28” almost always in cruise which usually means 370 or lower on the CHTs with cowl flaps closed.  Unfortunately my gami spread isn’t great, so I can’t run LOP very well and I avoid it until I can balance the injectiors. 

I wonder if your cylinders are still breaking in causing the heat. 

[jrwilson]

There is a spring on your cowl cowl flaps...yours is probably old and stretched.  Mine did the same thing, popping to full open and a new spring solved it.

[jrwilson]

A MSC should know the part

[tomatl]

Thanks, very helpful!


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[tomatl]

We have identified the cowl flap problem and fixed it. The Spring was attached to the firewall at the wrong point - moving the bracket one whole to the left (closer to the exhaust) fixed the problem.


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[jrwilson]

Good.  Nice and cheap resolution

[tomatl]

Yes, thanks! The beneficial effect is that the spring is stretched more and can move freely, which - in line with your suggestion - fixed the issue.


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